Check for mount point instead of symlink in finddata2dirent

Testing on a pnpm monorepo containing recursive symlinks, it turns out
that dwReserved0 is actually IO_REPARSE_TAG_MOUNT_POINT.

Checking FILE_ATTRIBUTE_REPARSE_POINT and IO_REPARSE_TAG_MOUNT_POINT
appears to match similar code in mingw.c's mingw_is_mount_point.

The new test fails without this change, but I am unsure whether or not
it needs some sort of conditional that checks that symlinks are
available in Windows. "SYMLINK" used in the test file appears to be
false even though I have developer mode enabled, allowing them.

Signed-off-by: Jake Bailey <jabaile@microsoft.com>

Author: jakebailey

compat/win32/dirent.c

@@ -19,7 +19,7 @@ static inline void finddata2dirent(struct dirent *ent, WIN32_FIND_DATAW *fdata)
 
 	/* Set file type, based on WIN32_FIND_DATA */
 	if ((fdata->dwFileAttributes & FILE_ATTRIBUTE_REPARSE_POINT)
-			&& fdata->dwReserved0 == IO_REPARSE_TAG_SYMLINK)
+			&& fdata->dwReserved0 == IO_REPARSE_TAG_MOUNT_POINT)
 		ent->d_type = DT_LNK;
 	else if (fdata->dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY)
 		ent->d_type = DT_DIR;

t/t7300-clean.sh

@@ -799,4 +799,26 @@ test_expect_success MINGW 'clean does not traverse mount points' '
 	test_path_is_file target/dont-clean-me
 '
 
+test_expect_success MINGW 'clean handles recursive symlink' '
+	rm -fr repo &&
+	mkdir repo &&
+	(
+		cd repo &&
+		git init &&
+		mkdir -p packages/some-package/node_modules &&
+		cd packages/some-package &&
+		touch package.json &&
+		git add package.json &&
+		git commit -m setup &&
+		cd node_modules &&
+		cmd //c "mklink /D /J some-package .." &&
+		cd ../../.. &&
+		test_path_is_file packages/some-package/package.json &&
+		git clean -fdx packages 2>err &&
+		test_path_is_file packages/some-package/package.json &&
+		test_path_is_missing packages/some-package/node_modules &&
+		! test_i18ngrep "warning" err
+	)
+'
+
 test_done